The goal of this project is to design and develop a lightweight portable headset device capable of recording EEG in human subjects to provide feedback reflecting the onset of drowsiness during their normal daily activities. The Drowsiness Monitoring Device (DMD) will incorporate an existing hybrid amplifier design to acquire high quality ambulatory EEG signals. An optional battery powered solid state digital recorder will provide ambulatory EEG recordings for off-line data reduction and analysis. In Phase I, data collection from 20 subjects will be used to develop computer algorithms to reject artifact and identify EEG indices of drowsiness in real time. The amplifiers will be redesigned to reduce power consumption, and include on-line calibration and impedance monitoring and specifications will be outlined for digital signal processing hardware. Phase II will focus on constructing an easy to use headset device including: an electrode placement mechanism, automatic diagnostic software and an auditory feedback system triggered by the detection of drowsiness in the EEG in real time. The complete system will be validated on a cross section of normal ambulatory subjects in their work environments. The final product is intended to prevent accidents caused by individuals whose occupations require sustained periods of vigilance (e.g. pilots, truck drivers etc.) and to assist those suffering from sleep disorders.